feat(series): multi-field search, sort-direction toggle, apply placement

Toolbar feedback round: the series search box now matches whatever the
main search matches for a group — series NAME, any book's AUTHOR, and
any book's TITLE inside the series (WHERE EXISTS per group-row, so
counts stay true); the separate author input is gone from the toolbar
(the author= param stays live for the JSON API and deep links). The
sort control becomes a base-key select (Date added/Name/Author/Books/
Progress/Last read) plus a chevron direction toggle that flips and
resubmits; sort/dir compose through ResolveSeriesSort (full registry
keys keep working for back-compat, unknown base keys fall to recent).
The search/apply button moved next to the search box as requested, and
default URLs stay clean (sort/dir only emitted once the user chooses).

internal/database/queries/queries.sql

@@ -4104,7 +4104,19 @@ WHERE (sqlc.narg('library_id')::uuid IS NULL OR library_id = sqlc.narg('library_
   AND archived_at IS NULL
   AND missing_scan_count = 0
   AND series IS NOT NULL AND series != ''
-  AND (sqlc.narg('series_query')::text IS NULL OR series ILIKE '%' || sqlc.narg('series_query')::text || '%')
+  -- Multi-field search (series page): the query matches the series
+  -- NAME, any book's AUTHOR, or any book's TITLE in the group. It is
+  -- a WHERE filter: a group qualifies when ANY of its rows matches,
+  -- so COUNT(*) keeps reporting the whole series.
+  AND (sqlc.narg('series_query')::text IS NULL OR
+       series ILIKE '%' || sqlc.narg('series_query')::text || '%'
+       OR author ILIKE '%' || sqlc.narg('series_query')::text || '%'
+       OR EXISTS (
+         SELECT 1 FROM media_items sib
+         WHERE sib.library_id = media_items.library_id
+           AND sib.series = media_items.series
+           AND sib.title ILIKE '%' || sqlc.narg('series_query')::text || '%'
+       ))
 GROUP BY library_id, series
 HAVING (sqlc.narg('author_query')::text IS NULL OR BOOL_OR(author ILIKE '%' || sqlc.narg('author_query')::text || '%'))
   AND (
@@ -4152,7 +4164,15 @@ SELECT COUNT(*)::int FROM (
     AND archived_at IS NULL
     AND missing_scan_count = 0
     AND series IS NOT NULL AND series != ''
-    AND (sqlc.narg('series_query')::text IS NULL OR series ILIKE '%' || sqlc.narg('series_query')::text || '%')
+    AND (sqlc.narg('series_query')::text IS NULL OR
+         series ILIKE '%' || sqlc.narg('series_query')::text || '%'
+         OR author ILIKE '%' || sqlc.narg('series_query')::text || '%'
+         OR EXISTS (
+           SELECT 1 FROM media_items sib
+           WHERE sib.library_id = media_items.library_id
+             AND sib.series = media_items.series
+             AND sib.title ILIKE '%' || sqlc.narg('series_query')::text || '%'
+         ))
   GROUP BY library_id, series
   HAVING (sqlc.narg('author_query')::text IS NULL OR BOOL_OR(author ILIKE '%' || sqlc.narg('author_query')::text || '%'))
     AND (